|
|
Labile elementosilicates as intermediates for design of novel materials
Yue, Qiudi ; Opanasenko, Maksym (advisor) ; Hronec, Mlan (referee) ; Zima, Vítězslav (referee)
Zeolites are crystalline microporous materials with three-dimensional frameworks built from corner-sharing TO4 tetrahedra. Traditionally, zeolites are defined as aluminosilicates (T = Si and Al). Nowadays, the skeleton atoms have been expanded to other tri-/tetra-valent elements, including B, Ga, Ge, Ti, etc., due to the chemical flexibility of zeolites. Resulting materials are termed as elementosilicates for respective element-containing zeolites. Such materials exhibit fascinating properties due to the different nature of elements in the framework, e.g. structural flexibility and tunable acidity. Taking advantage of the unique properties of elementosilicate zeolites, their applications as the starting solids for the synthesis of new materials and as adsorbents for gas separation have made great progress. However, the complexity of the factors affecting the zeolite synthesis limits the possibility to control the key parameters of zeolites formation, e.g. crystallization mechanism, crystal growth rate, and phase selectivity. From the another side, for particular zeolite systems being perspective for gas separation, correlation between the chemical composition of designed structures and their adsorption performance is elusive. Considering the above statements, this thesis was focused on the design...
|
|
|
Design and catalytic application of novel nanostructured materials
Zhou, Yong ; Opanasenko, Maksym (advisor) ; Bulánek, Roman (referee) ; Zima, Vítězslav (referee)
Zeolites are crystalline aluminosilicates and environmentally friendly solid acid catalysts thanks to their non-toxicity, large surface area, excellent (hydro)thermal stability, and tunable acidity. Traditionally, zeolite catalysts are applied in industrial processes related to petrochemistry, but several studies have recently shown their high potential in fine chemicals production and volatile organic compounds (VOCs) elimination. Advanced materials based on newly developed layered and nanosized zeolites have exhibited further fascinating properties, e.g., a short diffusion pathway, tunable structure and morphology. However, the limited correlation between key parameters of zeolite synthesis and their properties (structural, textural, acidic) and catalytic performance, especially for new layered and nanosized zeolites, hinders the development and application of zeolite catalysts. Considering the above, this thesis focused on the preparation of several sets of specific zeolite catalysts to gain further insights into the relationship between key properties of zeolites (structure, morphology, chemical composition, accessibility to acid sites or other functional groups, and organization of layers, among others) and their performance as catalysts, supports for other active phases or nanosized...
|
|
|
Design of zeolite materials with tailored interlayer structure and tunable textural properties
Kasneryk, Valeryia ; Opanasenko, Maksym (advisor) ; Zima, Vítězslav (referee) ; Shvets, Oleksiy (referee)
Germanosilicate zeolites attracted a lot of attention during the last decade. The reason for such interest is related to the unique structural properties of germanosilicates, which include zeolites of UTL, UOV, ITH, IWR, IWW, and CIT-13 types. The frameworks of these materials can be described as Si-rich layers connected by double four ring (D4R) units preferentially occupied by Ge atoms. Hydrolytic instability of Ge-O bonds in mentioned frameworks compared with Si-O bonds in conventional zeolites gives the opportunity for controllable chemically selective transformation of the germanosilicate frameworks towards novel types of zeolites including their 2D analogues. This PhD thesis focuses on modification of the structure and textural properties of germanosilicates using different ways of post-synthesis treatment: the ADOR (Assembly - Disassembly - Organization - Reassembly) transformation and post-synthesis degermanation and alumination. Presented work was carried out in the Department of Synthesis and Catalysis at J. Heyrovský Institute of Physical Chemistry in Prague under the supervision of Dr. Maksym Opanasenko and advising of Prof. Jiři Čejka. First way of post-synthesis treatment applied in this work was the recently developed method of zeolite synthesis - the ADOR transformation....
|
guest ::
